Nuclear fusion and energy
with
Some of the answers to the complexities of the climate system are given in my recently published book "Climate Change: A Realistic Perspective". In Chapter 12 on "Energy" the topics covered are (1) Fossil fuels, (2) Geothermal energy, (3) Nuclear energy, (4) Solar energy, (5) Wind power, (6) Hydroelectricity (7) Tidal power, (7) Biomass, and (8) Nuclear fusion, Below are extracts from pages 360-365 relating to Nuclear Fusion.
Nuclear fusion
Nuclear fusion is an attempt to replicate the processes of the Sun on
Earth. It differs significantly from nuclear fission, which has been our
only way of getting electricity from atoms since the 1950s. The BBC
website in a report on Nuclear Energy by Matt McGrath on November
6, 2019 says prospects for developing nuclear fusion as a feasible source
of energy have significantly improved. The UK government has recently
announced an investment of £200m to deliver electricity from a fusion
reactor by 2040. Private companies and governments have told the BBC
they aim to have demonstration models working within five years. But
huge hurdles remain, say critics.
With the price of wind and solar continuing to drop, experts say these
existing renewables might offer a more economical and timely method
of tackling climate change and generating energy than an unproven
technology like fusion. Fission has proven to be hugely expensive. It
generates large amounts of radioactive waste and raises serious concerns
about safety and the proliferation of weapons.
Fusion is the process that drives our Sun. Every single second,
millions of tonnes of hydrogen atoms crash together in the tremendous
temperatures and pressures of our parent star. This forces them to break
their atomic bonds and fuse to make the heavier element, helium.
Build the Sun in a box
For decades, researchers have been trying to replicate this process on
Earth, or “build the Sun in a box” as one physicist dubbed it. The basic
idea is to take a type of hydrogen gas, heat it to more than 100 million
°C until it forms a thin, fragile cloud called a plasma, and then control
it with powerful magnets until the atoms fuse and release energy.
Potentially, it can generate power that is low carbon, with much smaller
amounts of waste. It also comes without the danger of explosions. To
deliver the fusion concept, countries have focused their energies on a
major international co-operative effort called ITER. The BBC asks the
question is it “.. a giant step forward or a white elephant?”
The International Thermonuclear Experimental Reactor (ITER) project
involves 35 countries and, in 2020 it was constructing a huge test reactor
in southern France. The plan is to have the first plasma generated in
2025. However, getting from this step to producing energy is extremely
difficult. ITER has also been beset by long delays and budget overspend
which means it is unlikely to have a demonstration fusion power plant
working even by 2050. “One of the reasons that ITER is late is that it
is really, really hard,” said Prof Ian Chapman, chief executive of the UK
Atomic Energy Authority. “What we are doing is fundamentally pushing
the barriers of what’s known in the technology world. And of course you
reach hurdles and you have to overcome them, which we do all the time
and ITER will happen, I am completely convinced of it.”
Until ITER is up and running in 2025, the UK based Joint European
Torus (Jet) remains the world’s largest fusion experiment. It has secured
EU funding until the end of 2020, but what happens after that, and the
participation of the UK in ITER after Brexit remains unclear. To give
some sense of certainty, the UK government recently announced £220m
for the conceptual design of a fusion power station by 2040. Over the
next four years, researchers based at Culham in Oxfordshire will develop
designs for a fusion power plant called Step or Spherical Tokamak for
Energy Production.
The most widely known approach to making fusion happen involves
a doughnut shaped vacuum chamber called a Tokamak. Hydrogen gas
is heated to 100 million °C at which point it become a plasma. Powerful
magnets are used to confine and steer the plasma until fusion occurs.
In the UK, researchers have developed a different form of Tokamak,
that more resembles an apple core than a doughnut. Called a Spherical
Tokamak, it has the advantage of being more compact, potentially
allowing future power plants to be located in towns and cities.
“If you look at some of the very big units, the big machines that we
are looking at, just finding geographically somewhere to put them is
difficult,” said Nanna Heiberg from the UK Atomic Energy Authority.
“What you really want to do is put them close to where the energy is
required. And so if you can do them in a much smaller footprint, you can
put them closer to the users and you can put more of them around the
country for example.”
While governments are wrestling with ITER, many are also driving
ahead with their own national plans. China, India, Russia and the US
among others are working on developing commercial reactors.
As well as the UK government putting cash in, the European
Investment Bank is pumping hundreds of millions of euros into an Italian
programme to produce fusion energy by 2050. But perhaps the major
excitement comes from private companies. They are usually smaller,
nimbler, and they develop by making mistakes and learning from them
quickly. There are now dozens of them around the world, raising funds
and pushing forward often with different approaches to fusion than that
seen in ITER and in the UK.
Here’s a brief sample of some different approaches to fusion:
First Light: This company originated in the University of Oxford and
was founded specifically to address the urgent need to decarbonise the
global energy system. Their idea involves firing a projectile at a target
that contains hydrogen atoms. The shockwave from the impact of the
projectile creates a shockwave that crushes the fuel and briefly this
reaction will produce plasma that is hotter than the sun and denser than
lead.
Commonwealth Fusion Systems: A private company created by former
Massachusetts Institute of Technology (MIT) staff, CFS has raised
significant funding of over $100m. It is focusing on developing a Tokamak
system but its key innovation is in superconducting magnets. They hope
to build powerful enough magnets so they can build smaller and cheaper
Tokamaks to contain the plasmas required to generate fusion.
TAE Technologies: With backing from Google and other high tech
investors, this California-based company is using a different mix of fuel
to develop smaller, cheaper reactors. They want to use hydrogen and
boron as both elements are readily available and non-radioactive. Their
prototype is a cylindrical colliding beam fusion reactor (CBFR) that heats
hydrogen gas to form two rings of plasma. These are merged and held
together with beams of neutral particles to make it hotter and last longer.
US Navy: Worried about how to power their ships in the future, the
US Navy has filed a patent for a “plasma compression fusion device”.
The patent says that it would use magnetic fields to create “accelerated
vibration and/or accelerated spin”. The idea would be to make fusion
power reactors small enough to be portable. There’s a lot of scepticism
that this approach will work.
One of the main challengers with ambitions to make fusion work is a
company based in British Columbia, Canada called General Fusion. Their
approach, which has gathered a lot of attention and backing from the
likes of Amazon’s Jeff Bezos, combines cutting edge physics with off the
shelf technology. They call their system “magnetised target fusion”.
Despite the hopes, no one to date has managed to get more energy out
of a fusion experiment than they have put in. Most experts are confident
the idea will work, but many believe that it is a matter of scale. To make
it work, you have to go large. “I think fusion needs resources to really
make it work,” said Prof Ian Chapman from UKAEA. “You could do that
within a company or a country but you really need to have the requisite
scale and resources. When ITER works, and I say when, not if, it will be
a step change for fusion and you will see massive investment come into
the field.”
Will renewable energy make fusion redundant?
A relevant question is will renewable energy make fusion redundant? In
2018, the IPCC reported that emissions of CO2 need to be reduced by
45% by 2030 to keep the rise in global temperatures under 1.5°C. Getting
to that point requires a rapid decarbonisation of the energy sector. The
UK has committed to Net Zero emissions by 2050 which will require
the deployment of wind and solar on a massive scale. Some argue this
should be a greater priority for Britain, rather than spending large sums
on experimental fusion reactors.
“The cost of renewables has shot down
while the cost of the world fusion project, ITER, has gone up and it now
looks very unlikely they will be able to compete without new ideas,” said
Sir Chris Llewellyn Smith, a one time chair of the ITER council and a
respected British physicist. “I don’t think this means we should give up
on fusion, there are ways it could become cheaper but it is not going to be
there immediately when we need it in the UK at least.”
Others involved in the fusion industry take a different view. “If you’re
a country like Malaysia, that has a high carbon intensity of its energy
system, and you’re trying to move away from coal, there’s not a lot of
options today,” said Chris Mowry, General Fusion’s chief executive. “This
is the type of application we’re focused on. And even in countries like
Canada, which have a fair amount of renewables, it can never be 100%
renewables. And so we need a carbon free source of energy that can
complement renewables in the future.”
The Center for Nuclear Science and Technology Information website
says that Nuclear Fusion is a nuclear process, where energy is produced
by smashing together light atoms. It is the opposite reaction of fission,
where heavy isotopes are split apart. Fusion is the process by which the
Sun and other stars generate light and heat. It’s most easily achieved on
Earth by combining two isotopes of hydrogen: deuterium and tritium.
Hydrogen is the lightest of all the elements, being made up of a single
proton and an electron.
Deuterium has an extra neutron in its nucleus;
it can replace one of the hydrogen atoms in H2O to make what is called
“heavy water.” Tritium has two extra neutrons, and is therefore three
times as heavy as hydrogen. In a fusion cycle, tritium and deuterium are
combined and result in the formation of helium, the next heaviest element
in the Periodic Table, and the release of a free neutron. Deuterium is
found one part per 6,500 in ordinary seawater, and is therefore globally
available, eliminating the problem of unequal geographical distribution
of fuel resources. This means that there will be fuel for fusion as long as
there is water on the planet.
Scientists from the Max Planck Institute for Plasma Physics in
Greifswald, Germany, have demonstrated that it is possible to superheat
hydrogen atoms to form a plasma of 80 million °C using a machine called
the Wendelstein 7-X stellarator. The plasma forms the basis for nuclear
fusion, in which hydrogen atoms collide and their nuclei fuse to form
helium atoms – a process which lets off energy and is similar to what
happens in our sun.
What is Fusion Power? Let’s take look at a fusion reaction. As deuterium
and tritium fuse together, their component parts are recombined
into a helium atom and a free neutron. As the two heavy isotopes are
reassembled into a helium atom, you have ‘extra’ mass leftover which is
converted into the kinetic energy of the neutron, according to Einstein’s
formula: E = mc2
For a nuclear fusion reaction to occur, it is necessary to
bring two nuclei so close that nuclear forces become active and glue the
nuclei together. Nuclear forces are small-distance forces and have to act
against the electrostatic forces where positively charged nuclei repel each
other. This is the reason nuclear fusion reactions occur mostly in high
density, high temperature environment.
World’s Largest Nuclear Fusion Experiment Clears Milestone
From the website Climatewire and in the E+E News dated July 24, 2019,
as reported in the Scientific American, Nathanial Gronewold said that
The International Thermonuclear Experimental Reactor is set to launch
operations in 2025. The International Thermonuclear Experimental
Reactor is under construction in southern France.
A multination project to build a fusion reactor cleared a milestone in 2020
and is now 61⁄2 years away from “First Plasma,” officials
announced. Dignitaries attended a components handover ceremony at
the construction site of the International Thermonuclear Experimental
Reactor in southern France. The ITER project is an experiment aimed at
reaching the next stage in the evolution of nuclear energy as a means of
generating emissions-free electricity. The section recently installed–the
cryostat base and lower cylinder–paves the way for the installation of the
tokamak, the technology design chosen to house the powerful magnetic
field that will encase the ultra-hot plasma fusion core.
“Manufactured by India, the ITER cryostat is 16,000 cubic metres,”
ITER officials said in a release. “Its diameter and height are both almost 30
metres and it weighs 3,850 tons. Because of its bulk, it is being fabricated
in four main sections: the base, lower cylinder, upper cylinder, and top
lid.” The entire project is now 65% complete, the officials said. The world’s
first commercial-scale fusion reactor project is on track to officially
launch operations at the end of 2025, said spokeswoman Sabina Griffith,
but it will take at least a decade to fully power up the facility. “The date for
First Plasma is set; we will push the button in December 2025,” Griffith
said. “It will take another 10 years until we reach full deuterium-tritium
operations.” Thirty-five nations are cooperating on the project to bring
fusion power to the masses.
A potential answer to climate change
Achieving controlled fusion reactions that net more power than they
take to generate, and at commercial scale, is seen as a potential answer
to climate change. Fusion energy would eliminate the need for fossil
fuels and solve the intermittency and reliability concerns inherent with
renewable energy sources. The energy would be generated without
the dangerous amounts of radiation that raises concerns about fission
nuclear energy. Officials say the ITER nuclear fusion reactor is poised to
be the most complicated piece of machinery ever built. It will contain the
world’s largest superconducting magnets, needed to generate a magnetic
field powerful enough to contain a plasma that will reach temperatures of
150 million °C , about 10 times hotter than the centre of the sun.
“We will see the arrival of the first major Tokamak components like
the first PF Coil from China (a European contribution), a Vacuum Vessel
sector from Korea and first TF coils (from Europe and Japan) in autumn,”
Griffith said in an email. “This will lead us to the official start of the assembly in spring next year".
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